REEDS swaying in the breeze, egrets picking their way about mudflats, seagulls dive-bombing for a fish and marsh critters just going about their business. This tranquil scene is just within an hour's ride from frenetic downtown Shanghai.

Amazing proximity.

Even more amazing is the fact that three years ago, vast heaps of steel slag and junk were encroaching, the water was murky, the air was foul. These 50 hectares of natural wetland ?? far smaller than the vast original ?? and their native inhabitants could easily have been wiped out by reckless industrialization.

The Baoshan District government decided otherwise, however, and in late 2005 began a herculean task of environmental cleanup, protection and greenery planting in a wetland rescue.

The aim is to preserve the wetland ecosystem that functions as "the kidney of Earth," nature's filter, its water and air purifier.

The result is Paotaiwan (Emplacement) Wetland Park, Phase I, open to the public since May 2007. It now includes another 50 hectares of land that is expected to add another 20 hectares by the time the Shanghai World Expo opens in May 2010.

The wetland received the China Habitat Environment Award in January.

The riverside park lies in Wusong area, Baoshan District, in the north of Shanghai, where the Huangpu and Yangtze rivers meet. It has a 2-kilometer-long waterfront along the Yangtze River and is part of an ambitious plan to redevelop Baoshan's riverside parks.

Here the Yangtze River slows as it approaches the estuary; mud and sand carried by the river precipitate in the process and form wetland where water plants, water birds, fish and many animals thrive.

The wetland covers more than 50 hectares and the park includes another 50 hectares.

Phase I construction was launched in late 2005 and completed in early 2007, according to Yang Xin, president of the Shanghai Baoshan Greening Management Bureau.

It is Shanghai's second-largest wetland park only after the Chongming Dontan Wetland on Chongming Island.

A winding plank walkway lets visitors approach the river and enjoy the wetland on either side. Small fish swim about, crabs crawl on the mudflats, egrets strut about and wing their way above, seagulls dive downward to catch fish.

"Many egrets arrived in our wetland in the big snow period early last year," says Liu Shengde, deputy Party secretary of the Shanghai Baoshan Greening Management Bureau. "It was so amazing to see them strut around on the white snow."

Apart from the natural wetland, the park also has gardens and man-made forest, lawns, hills, waterfalls and streams. There are more than 13,000 trees of 53 varieties, including ginkgo, maple, cherry, bay and camphor, as well as 300,000 bushes of 77 varieties. Flowers are abundant in all seasons.

This is a place where visitors can get close to nature, but just three years ago it presented a totally different and very grim picture.

"Industrial refuse like steel slag was piling up all over. There was unauthorized construction and junkmen gathered there, making it a dirty and dangerous place," says Yang.

The wetland at Wusong estuary came into being ages ago. Its special location, the "throat" of both Huangpu and Yangtze rivers, made it a stronghold for China's coastal defense over the years.

An emplacement was built there to guard the interior in the Qing Dynasty (1644-1911), thus it was called "Paotaiwan."

It was important in the Opium Wars (1840-42), the War of Resistance Against Japanese Aggression (1937-45) and the Chinese Civil War (1945-49). After liberation, naval, air and land forces were garrisoned nearby. A hill was built upon waste steel and used for military purposes in the 1960s. It was covered with greenery and known as Paotai Hill.

Most of wetland and scenery was destroyed later through rapid industrialization without environmental management. Polluting steel factories near the wetland simply dumped steel slag and other waste at the river bank, turning the riverbank into a refuse dump.

"Some piles of steel slag were more than 10 meters high; the dump nearly bordered the wetland," says Yang. "When it rained, the slag would flow into the river, making it dark and dirty. When the wind blew, the slag particles were caught in the air, making it choking."

And the many unemployed junkmen in the area also posed a threat to public security.

Therefore, the Baoshan District government decided in 2005 to clean up the area and revive the wetland. All the steel slag (the leftover from smelting ore) was buried deep. Soil, plants and trees were brought in and an ecological park was set up along the riverbank.

"Unlike chemical discharges, steel slag won't damage the environment when it is buried deep," says Yang. "And the soil and plants above can help purify the water and soil."

Protecting what's left of the original wetland is a major task.

"The 50-hectare wetland is a precious treasure for the ecosystem here," says Yang. He calls wetland "the kidney of Earth," a purifier and filter that protects water resources.

Ecologists call wetlands transitional areas between terrestrial ecosystems and aquatic systems; the two systems are inherently different from each other, yet dependent on each other. They meet in the wetlands that are places of great biodiversity. Many water birds only reproduce in wetlands.

Wetland, forest and ocean are considered the three great ecosystems.

Wetland not only provides a friendly habitat for many creatures but also protects water resources on the land. Polluting substances in water will naturally precipitate when a river or stream flows slowly through a wetland; toxins will break down while nutrients will nourish plants.

Wetlands can help prevent drought and flood through its exchange between underground water and surface runoff. They also can prevent seawater from invading the land and freshwater.

Yet the "kidney of Earth" couldn't possibly purify the many tons of refuse along the river in Baoshan District. No water birds or migratory birds would ever nest where the water was dark and smelly and the air was suffocating.

"Luckily, with our efforts, we have successfully turned the dump back into an ecological area," says Yang. "Water plants like wild water bamboo are found again here and many birds have discovered this wonderful habitat. You will find seagulls there these days."

The park was opened to the public in May 2007. Because of the damage that too many visitors can cause, officials decided to charge 5-yuan admission to discourage too many sightseers. The original plan had called for free admission.

It took about 150 million yuan (US$22 million) to move the refuse piles and build the first phase of the park, according to Yang. Another 300 million yuan will be spent to complete Phase II of an additional 20 hectares.

"We plan to complete an ecological zone along the riverbank in time for World Expo 2010 opening in May 2010," says Yang.

Opening hours: 5am-5pm (free during 5-7am)

Address: 206 Tanghou Rd, Wusong, Baoshan District

Admission: 5 yuan

Tel: 5657-9007

Wetlands in China

China has more than 66 million hectares of wetland, representing 10 percent of the world's total ?? the largest wetland area in Asia and the fourth-biggest in the world.

There are 31 kinds of natural wetland and nine man-made wetland, according to the International Convention on Wetlands. They include natural marsh wetland, river wetland, littoral wetland and reservoir wetland. These are scattered throughout China, from the cool temperature zone to tropical area, from coast to inland, from plains to plateau.

Eastern China is rich with river wetland; the northeast has marsh wetland; lake wetlands are found in the middle and lower reaches of the Yangtze River and the Qinghai-Tibet Plateau; mangrove and man-made wetland in tropical areas are found in Hainan and Fujian provinces.

China's wetlands support thousands of plant and animal species. There are around 5,000 species of plants and 3,200 species of animals in littoral wetlands, and around 1,560 species of advanced plants and 1,500 species of advanced animals in wetlands inland.

China has about 770 species of freshwater fish, including many migratory fishes that only reproduce in wetlands. Thirty-one of the 57 endangered bird species in Asia are found in China's wetlands. China also has 50 of the 166 species of geese and ducks and nine of the 15 species of cranes.

Some wetlands are mandatory stop-overs for some migratory birds, such as the Poyang Lake Wetland for white cranes in Jiangxi Province.

Wetlands have shrunk dramatically in recent years due to human activities. About half of the littoral mudflats, 80 percent of the natural marsh wetlands at Sanjiang Plan in northeastern Heilongjiang Province and 1,000 natural lakes disappeared by the mid-1990s.

China joined the International Convention on Wetlands in 1992 and started its work on wetland protection.

So far, 30 wetlands in China are on the authoritative Ramsar (after a small town in Iran where the convention was signed) List of Wetlands of International Importance.

They include the Zhalong Nature Reserve in Heilongjiang Province, Poyang Lake Nature Reserve in Jiangxi Province, Dongting Lake Nature Reserve in Henan Province and Chongming Dongtan Natural Reserve on Chongming Island (County) in Shanghai.